apologies for not saying something sooner due to sometimes, things can fall through the cracks with everything i try to do...
i agree with ax and crosspotts that this is pretty cool.
here is an idea, take a cue from mystique by zvitor. he has some code in there that has mystique shapeshift into whoever she is fighting for 1 attack. maybe you could do similarly. that would mean a truly unique attack depending on whoever you are fighting.
also, something else you seem to want to do is get representatives from other games. well, cyclops probably the best rep for x-men related fighters. batman the same from dc ones, though couldnt go wrong with superman (try tumatae's excellent version) either.
something else could try, random projectiles. throw a projectile at P2, and have it randomize out of various versions of whatever other fighting game projectiles.